switch room

--my code
CREATE PROCEDURE  usp_SwitchRoom(@TripId INT,@TargetRoomId INT)
AS
    BEGIN

    DECLARE @InitialHotel INT= (SELECT h.Id FROM Hotels AS h
                            JOIN Rooms AS r ON h.Id=r.HotelId
                            JOIN Trips AS t ON t.RoomId=r.Id
                            WHERE t.Id=@TripId)
--ako se mahne trips join  в @newhotel  минава с 7/7...
    DECLARE @NewHotel INT=(SELECT h.Id FROM Hotels AS h
                            JOIN Rooms AS r ON h.Id=r.HotelId
                            JOIN Trips AS t ON t.RoomId=r.Id
                            WHERE  r.Id=@TargetRoomId)
    DECLARE @NewBeds INT=(SELECT r.Beds FROM Rooms AS r
                                WHERE r.Id=@TargetRoomId)

    DECLARE @NumPeople INT=(SELECT COUNT(act.AccountId) FROM Trips AS t
                                JOIN AccountsTrips AS act ON t.Id=act.TripId
                                WHERE t.Id=@TripId)

    IF (@InitialHotel<>@NewHotel)

    RAISERROR('Target room is in another hotel',16,1)


    IF(@NumPeople>@NewBeds)
        RAISERROR('Not enough beds in target room!',16,1)


      UPDATE Trips
      SET RoomId=@TargetRoomId
      WHERE Id=@TripId
END
GO
-- authors code
CREATE OR ALTER PROC usp_SwitchRoom(@TripId INT, @TargetRoomId INT)
AS
  BEGIN
    DECLARE @SourceHotelId INT = (SELECT H.Id
                                  FROM Hotels H
                                    JOIN Rooms R ON H.Id = R.HotelId
                                    JOIN Trips T ON R.Id = T.RoomId
                                  WHERE T.Id = @TripId)

    DECLARE @TargetHotelId INT = (SELECT H.Id
                                  FROM Hotels H
                                    JOIN Rooms R ON H.Id = R.HotelId
                                  WHERE R.Id = @TargetRoomId)

    IF (@SourceHotelId <> @TargetHotelId)
      THROW 50013, 'Target room is in another hotel!', 1

    DECLARE @PeopleCount INT = (SELECT COUNT(*)
                                FROM AccountsTrips
                                WHERE TripId = @TripId)

    DECLARE @TargetRoomBeds INT = (SELECT Beds
                                   FROM Rooms
                                   WHERE Id = @TargetRoomId)

    IF (@PeopleCount > @TargetRoomBeds)
      THROW 50013, 'Not enough beds in target room!', 1

    UPDATE Trips
    SET RoomId = @TargetRoomId
    WHERE Id = @TripId
  END